Manufacture of electron discharge devices



; April 24, 1945.

J. P. LAICO MANUFACTURE OF ELECTRON DISCHARGE DEVIC ES Filed Jan. 21',1941 INVENTOR J R LA/CO 0mm auw Patented Apr. 24, 1945 Joseph P; Laico,Brooklyn, N. 1, -assignor, togBell Telephone Laboratories,:Incorporated, .New

York,N.=Y.,a corporationof New York t y -Application January 21,1941,"SerialNo. sis-4101' (o1. zso-a'zrs) 5 Claims. This inventionrelates to the manufacture of .electron discharge devices, and moreparticularly i tomethods of manufacturing electron. beam dis- .;chargedevices such,-for.exan1ple, as beam devices of the velocity, variationtype.

. ,Electron beam discharge, devices of the type to which .this inventionpertains usually ,comprise two or more electrodes in energy transferrin-relationlwithrthe electron beam. Theattainment, ofdesiredoperatingcharacteristics, efii- ;cient operation, and operationat. ultra-high. frenquencies requires thattheseelectrodes bemount- .edinexact predeterminedrelation. and extreme- .ly close to one: another.-,lFor example, in some velocity variation devices, the requisite spacing:bGtWBB'I'LBIBCtIOdGS defining the input and. output gaps isextremelysmall and the allowable tolerances-are, but a few tenthousandths ofanzinch and,.in cases-where these electrodesarev apertured, forexampleannular, the electrodes must be in exact alignment. Such.electrodesxmaybe mounted in spaced relationbyinsulating members, forexample ofvitreouswmaterial, to-or in --which they aresealed.

The exact spacing of suchelectrodes mounted 1:.

,in this mannerheretofore has-beenextremely ,dificult'to obtain .due tothe factthat exact .de-

termination ofthe spacing by viewing has been impossible and due totheifurther fact that-the working of the vitreous-materialandthecontraction and expansion thereof during-the mal:-

ingot-the seals-thereto has notbeen accurately controllable to: enablethe realization within vextremely close limits of the ultimately desiredspace relationof the electrodes. l

One. object of this inventionis to facilitate the manufacture ofelectron discharge devices .in-

cluding a plurality of closely spaced electrodes. .More specifically,one object of i this invention is.-.,to facilitate the'mounting of aplurality of electrodesin an electron discharge device inexactralig-nment and -in accurate and extremely close space relation.

In accordance withone feature-of thisinvention, the several electrodesare provided with annular :mounting or supporting portions and tubularvitreous .members are hermetically sealedin coaxial relation to oppositefaces of the mounting portions. The electrodes to,-be =-mou-nted.in..-adjacent relation are then fitted upon a tool-or guidewiththetubularvitreous members ,of the two in abutting relation, the toollocating the twoelectrodes in ,exact coax iallyarid allowing relativelongitudinal movemembers are then heated to seal them together,

the necessary working of the vitreous material being accomplished Qhyrelative longitudinal movement ofthe electrode. "The tool is soconstructedthat the electrodes arelocated accurate- "lyin'th'e exactspace relation desired, when the vitreous material cools andithe seal isformed.

The invention and the foregoing and other features thereof will beunderstood more clearly and fullyfrom' theffollowing detaileddescription with reference to the accompanying drawing in which:

"Fig; 1 is a view in elevationofanelectronbeam discharge device of the.velocity variation type constructed accordance with this invention, aportion of the device being shown in section to. illustrate'the'formandrelation of certain of the electrodes nore clearly;

' Fli 2. isfa detail view insection of a portion .of the discharge"devicev illustrated ,in Fig. 1,

showing the variousfelectrode andinsulator assemblies. to .be mounted,prior to the sealing together thereof; M

.Fi B is aidetail view insectionnf oneof the electrodes and a toolusedinconjunction therewith duringthe. sealing of the insulating,membersthereto; H

Fig. 4' is, another ,detail view mainly insection illustrating themounting of another. of theelectrodes during the sealing of. theinsulatingmembers thereto;

Fig, .5, is still another detail view in-section il lustrating themannen otpositioning several of the electrode and insulator assembliesduring the Ijoining thereof;

, Figs. 6 and, 7.. are, fragmentary views. in, section illustratingother electrode assemblies constructed inaccordance with this,invention; and l i Fig. 8 is a viewhin section illustrating-another wayof positioning electrode and insulatorunits duringthe joining thereof.

Referring ,now',.to the drawing the electron beam discharge devicecomprises an evacuated enclosing vessel having an, elongated cylindricalportion lll, an .anode or target electrode .ll

mounted near one end of the cylindrical portion In and ,anelectron.gunJZ, which, may be of the construction disclosed in Patent. 2,303,166,grantvedNovemberzr, 1942,, to Joseph P, Laico, mounted opposite theother-end of the cylindrical. portionlll,

Mounted between thelelectron gun, l2 and the shock: or ,target electrodeH are.a plurality .of

coaxial electrodes .l3 to ll, inclusive, ,each of ,ment of-theelectrodes. The abutting vitreous 56 which. inC udQSanafi m y a- -l cppe tral frusto-conical portions 20, and the electrode l includes acentral, annular inwardly curved portion 2!. The electrodes l3 and. Mare spaced to define an input or control gap 22 and the electrodes l6and I! are spaced to define an out-.

put gap 23.

The operating characteristics of thedevice are I dependent in a largemeasure upon thesegaps' For example, efli cient operation and electrical"positioning or guide member or tool, for example symmetry of theelectrodes with respect to the beam whereby uniform transfer of energybetween I the electrode and the beam may be realized re- ,quire that theelectrodes bein exact coaxial relation. Furthermore, particularly atultra-high frequencies, gaps of extremely short length and greataccuracy, for example with tolerances-of the order of five tenthousandths of an inch, are required. Both the requisite exactcoaxiality .and

accurate-close spacing are attained facilely in devices'constructed inaccordance with this invention. v

As illustrated lar portion [8 of each of the electrodes l3 to H,inclusive, has hermetically sealed to opposite 'faces thereof lengthsofcylindrical, e. g., vitreous, tubing 24a and 2411 which are coaxialwith one another and the electrode to which they are sealed. The sealingbetween the annular porin Fig. 2., in manufacturing de; vices in.accordance with this invention, the annutions I 8 and the vitreoustubing s and 241) may be effected as illustrated in Figs. 3 and 4.

As shown in the former figure, thefi'usto-co'nical,

member 20- of' the electrode l4 or it is fitted on ya metallic o-rinsulating guide 25 which is mounted 'slidably on a rod 26 coaxialtherewith and which may be supported between chucks, not shown. Theelectrode maybe clamped to the guide 25by a collar 21having an innerfrustoconical wall conforming to the frusto-co-nical member 211 andwhich is detachably locked to the guide 25 by a hairpin shaped wire 28having outwardly bent ends as shown. The vitreous tubings 24a and 2417are positioned by the chucks, in coaxial relation with the rod 26 sothat when the tubing, is hermetically sealed to the annular portion 18by the application of. heat thereto in known ways, the coaxiality of theelectrode and 28 is withdrawn and the guide 2 5 and collar 21 areremoved as is also the guide 26; p

The seals between the electrode 15 and the lengths of tubings 24aandZl'b associated therewith may be made in thesame manner, as shown 29and'detachably locked thereto by one or more spring wiresMlhaving-bent-over ends as shown.

.4. is completed the annularportion [8 of the electrode l5 extendshormal to the longitudinal axis in Fig. '4. The electrode I5 is mountedon a guide of the unit. After the seals'be'tween thisportion l8 and theinsulating tubes 24a and Nb have been tioning member or tool have beenconstructed as described above, the units are joined to one another in amanner which assures the attainment of both exact coaxiality of theelectrodes and accurate spacing thereof. These ends may be realizedthrough the use of a of tungsten or stainless steel, which, asillustrated in Fig. 5, includes an end portion 32 having a surface whichconforms accurately to the central portion 2! of the electrode, l5, afrustoconical portion 33 which fits accurately within the portion 20 ofthe electrode H1 (or IS), an end portion 34 accuratelyfitted within thecylindrical portion [9 of the electrode l3 (or IT) and an intermediateportion 35 forming a seatagainst which the electrode I 3 (or IT) abuts.The posiis .slidably mounted upon a rod 36. I

In joining the units, the electrodes Hi and IT together with theassociated insulating tubes ma 'be'mounted upon the insulating member ortool with the tube 241) of the former inend-to-end relation with thetube 24a of the latter. The

facing ends of the two lengths of tubing are then heated, as by flamesplayed thereon. to render them plastic, and these lengths are thensealed is possible; as is apparent, to allow the necessary working ofthe vitreous material at the plastic ends without altering the coaxialrelation of the two units being joined. After the vitreous material hasbeen worked properly, the electrode I6 is positioned so that thefrusto-conical portion 20 thereof is firmly fitted upon the port on 33of the tool andthe electrode I1 is moved toward the between the abuttingtubings 24a and Nb forms.

'The portions 33 and 35 are so dimensioned that when the electrode llabuts the seat therefor. the spacing between the electrodes l6 and IT isexactly that desired for the gap 23. I A seal is then made in a similarmannerbetween thetub ng 24b associated with the electrode l6 and thetubing 24a associated with the electrode l5,the portions 32 and 33' ofthe tool being so dimensioned'that when the electrode members 2i and 20respectively are in firmlengagem'ent therewith, the electrodes are inexactly th'e'space relation desired in thecompleted device. 7 After thethree electrode-insulator units have been joined as described, the tooland rod 36 are withdrawn. A similar assembly is formed in like manner ofthe electrodes 13 and "arid the. insulating tubings' associatedtherewith. The

the two'assemblies are mounted in coaxial relation," and the tubing 24aassociated with the elec trode I4 is joined to the tubing 2% associatedwith the electrode iii. The two assemblies may bei located,longitudinally 'gduring .the making of .the: final seahby an'externalyspaocrz :engagingthe x annularportionsl I 8 of the aelectrodesr I4 and; I5.

*ItaWill be. apparentdthat im the assembly Tthus formed, all of r the.electrodesrare inexact coaxial ;re1ation: andthespacingsybetweemadjacent 291E- trodes tare .accurately; fixed so, that.a; device 10f i which this assembl forms ,ag'part will have: the

shown, for example, in Figs. 6 and 7. As shown in Fig. 6, the endmostelectrodes of the assembly include central frusto-conical portions 31,the

central electrode includes an annular central portion 38 and theintermediate electrodes include centrally apertured dished portions 39.As shown, several of the electrodes may be provided with an annularcorrugation 40 to allow expansion and contraction thereof during thefabrication and operation of ithe device and thereby to prevent thesetting up of deleterious stresses at the seals between the annular discportions l8 of the electrodes and the tubular portion III of theenclosing vessel and also to minimize variations in the space relationof the electrodes.

In the construction illustratelsl in Fig. '7, the central electrode isan annular disc 4| and the other electrodes are provided with coaxialcentral cylindridal portions as shown.

In cases where the electrodes are of such configuration that thelongitudinal spacing thereof cannot be fixed by a guide or tool of thegeneral construction shown in Fig. 5, apparatus of the constructionshown in Fig. 8 may be employed during the joining of twoelectrode-insulator units to one another. In the constructionillustrated in this figure, the electrodes comprise centralfrustoconical portions- 42 in end-to-end relation and annular portionsI8 sealed to vitreous tubings 24a and 24b in. the manner describedheretofore. The two electrodes, together with the insulating tubingassociated therewith, are mounted in coaxial relation by a cylindricalguide 43 having openings in its wall through which spacers 44 extend,the spacers being dimensioned accurate- 'ly so that when the electrodeportions 42 abut thereagainst, these portions will be in exactly thespace relation desired in the discharge device. The spacers 44 arecarried by resilient sulpporlts 45 fitting in internal grooves in theguide 43. The guide 43 is slidably fitted upon a rod 46 which isinsertable between the supports 45 and when thus inserted separates thespacers 44 so that they project from the guide 43. After the tubings 24aand 241) are sealed to one another, during which operation the electrodepore tions 42 are located accurately with respect to one another byvirtue of the abutment thereof against the spacers 44, the rod 46 iswithdrawn, the spacers 44 are forced within the guide 43 by pressing thesupports 45 toward each other, and the guide 43 is withdrawn. In theassembly thus formed, it is apparent that the two electrodes are mountedin exact coaxiality and are accurately spaced the distance desired.

Although specific methods and apparatus have been described, it will beunderstood that they are but illustrative and that various modificationsmay be made therein without departing from 75 the; scope andaspirit ofthis. :inventiomasodeflned l in theaappended'claims. What is claimedzis:M l

In the manufacture of l welectron discharge 1 devices includinga tubular1 insulating member 1 and a: plurality "ofaelectrodes wwithin.said;member and having conductive .portions uhermetically sealed to-said.member the method which com- ,prises, sealing a. tubular, lengths ,of;insulating rma- .terial to. opposite? faces-ofi each iofrsaid conductiveportions, mountingseveral, of; the assembliesathus formed in alignment,axially movable with respect to one another and with tubular lengths ofsuccessive of the assembliesin abutting relation, and

hermetically sealing the abutting tubular lengths to one another.

2. The method of constructing a unitary assembly for electron dischargedevices including a tubular insulating member and a plurality ofelectrodes Within said tubular member and having conductive portionssealed thereto, which method comprises sealing coaxial tubular lengthsof insulating material to opposite faces of each of said conductiveportions and in coaxial relation therewith, mounting several of theassemblies thus formed in coaxial relation, longitudinally movable withrespect to one another and with the tubular lengths of successiveassemblies in abutting relation, locating said assemblies so that theelectrodes included therein are in fixed, coaxial space relation, andhermetically sealing the abutting tubular lengths to one another.

3. In the manufacture of an electron discharge device including atubular insulating member and a plurality of electrodes within saidtubular member and having annular disc portions hermetically sealed tosaid member, the method of assembly which comprises sealing tubularlengths of insulating material in coaxial relation to opposite faces ofeach of said disc portions, mounting several of the assemblies thusformed in relative longitudinally movable relation upon a guide havingportions for locating the assemblies in coaxial relation and fordetermining the spacing between the electrodes in said assemblies, withtubular lengths of successive assemblies in abutting relation, softeningthe ends of said abutting tubular lengths, shifting adjacent assemblieslongitudinally to engage the electrodes thereof with said spacingdetermining portions, sealing abutting tubular lengths to one another,and withdrawing said guide.

4. The method of manufacturing an electron Hg discharge device includinga tubular insulating portionand a pair of electrodes within saidportion, each of said electrodes having a central portion and an outerannular disc portion hermetically sealed to said insulating portion,which method comprises sealing tubular lengths of insulating material incoaxial relation to opposite faces of each of said disc portions,mounting the assemblies thus formed upon a guide having coaxial portionsadapted to fit said central portions of said electrodes and havingthereon locating means for positioning the electrodes in predeterminedrelation, said assemblies being mounted on said guide so as to berelatively movable longitudinally and with one tubular length of oneassembly in juxtaposed relation with one tubular length of the otherassembly, heating the juxtaposed ends of said tubular lengths to renderthem plastic, sliding said assemblies longitudinally on said guide untilthe electrodes therein abut said locating means, hermetically sealingsaid juxtaposed ends to ether, and withdrawing said guide.

5. In the manufacture of an electron discharge device including atubular vitreous member and a pair of spaced electrodes within saidmember, each of said-electrodes having a central apertured portion andan annular supporting portion hermetically sealed to said vitreous'member, the

method which comprises sealing tubular lengths of vitreous material toone iace of each of said annular portions, mounting the assemblies thusformed in coaxial and longitudinally movable relation upon a guidehaving portions adapted to fit within said aperturedportionsof saidelec-- To another, and withdrawing said guide.

JOSEPH P. LAIco.

